January 1992, a freighter crossing the Pacific from Hong Kong to Tacoma, Wash., ran into rough weather near the International Date Line. As the ship heaved through the storm-tossed seas, several cargo containers on deck—including one filled with tens of thousands of plastic tub toys—came loose, fell overboard, and broke apart. Seven months after the spill, the plastic ducks, beavers, turtles, and frogs began washing up on beaches. Scientists who track ocean currents were ecstatic.

Even today, additional members of the tub-toy armada occasionally make landfall. The date and place of each of the nearly 1,000 toys recovered to date provide a data point, says Curtis Ebbesmeyer, a retired oceanographer in Seattle. Some of the toys are well traveled indeed—one frog washed ashore in Scotland, and a duck turned up near Maine. However, most of the drifters have remained stuck in the Pacific Subarctic Gyre, a set of deepwater and surface currents spanning an area the size of the continental United States that generally flows counterclockwise around the northern Pacific Ocean.